The use of combined gas chromatography/mass spectrometry to provide in routine manner qualitative analyses and stable isotope content data on tiny quantities of material, is now commonplace. Notwithstanding the full potential of the technique has yet to be tapped. In particular the value of the instrumentation in yielding information on such complex biological problems as cell differentiation, hormone induced physiological change has yet to be realized. The core research project of the Facility for Biomedical Research which we are presently establishing will concern itself with applying combined gas chromatography-mass spectrometry to such biological problems. The Facility will be based on the use of a single focusing mass spectrometer equipped with a gas chromatographic input, fast data acquisition, processing and presentation system, and stable and radioisotope measurement instruments. The model system studied will be the induction of secondary metabolism in fungi. In addition to core research, service work will be performed. This service will be of two types. Firstly, simple mass spectrometric measurements will be performed for medical scientist and related personnel in the regional area. Adequate interpretive and consultative service will simultaneously be provided. Secondly, interested investigators will have made available to them, in service form, the methodological and instrumentational advances made in physiological state definition as a result of core research activity.